It is often desired to form copolymers from monomers that have reactivities that differ from each other. Processes that attempt to make such copolymers sometimes result in one or more of the following outcomes: nonuniform polymer composition, nonuniform polymer molecular weight, high level of residual monomer, or any combination thereof. For example, U.S. Pat. No. 5,110,883 presents one method of addressing these problems, using a solution polymerization method in which all of the desired diallyl ammonium monomer and a portion of the desired acrylamide monomer are mixed together and initiated; in which the remaining acrylamide monomer is added by continuous stage addition; and in which chain transfer agent is added after the completion of polymerization.
It is desired to provide a copolymerization process for monomers with reactivities that differ from each other. It is desired to provide such a process that does not require placing all of the desired low-reactivity monomer into the reaction vessel prior to beginning the copolymerization process. It is also desired to provide such a process that results in one or more of the following additional benefits: uniform polymer composition, uniform molecular weight, or low levels of residual monomer.